Simplify the following expression: $a = \dfrac{6}{7n} \div \dfrac{4}{9n}$
Answer: Dividing by an expression is the same as multiplying by its inverse. $a = \dfrac{6}{7n} \times \dfrac{9n}{4}$ When multiplying fractions, we multiply the numerators and the denominators. $a = \dfrac{ 6 \times 9n } { 7n \times 4}$ $a = \dfrac{54n}{28n}$ Simplify: $a = \dfrac{27}{14}$